Lower fatty carboxylic acid alkyl ester production method

ABSTRACT

The present invention provides a method for producing a light fatty acid alkyl ester with the formula of R 1 —COO—R 2 , and the method comprises a step in which a alkyl ether with formula of R 1 —O—R 2  and a raw gas containing carbon monoxide go through a reactor loaded with a catalyst for carrying out a carbonylation reaction; wherein the catalyst contains an acidic EMT zeolite molecular sieve; wherein R 1  and R 2  are independently selected from C 1 -C 4  alkyl groups. The present invention has provided a new method for producing light fatty acid alkyl ester. In the method of the present invention, the carbonylation is carried out in the presence of the catalyst containing the acidic EMT zeolite molecular sieve, and the reaction activity is high, and the stability has been significantly improved, meeting the requirement of industrial production.

TECHNICAL FIELD

The present invention refers to a method for producing light fatty acidalkyl ester and the derivatives thereof by carbonylation of lower alkylethers, and particularly refers to a method for producing methyl acetateand its derivatives by carbonylation of dimethyl ether.

BACKGROUND

Accompanied with the rapid development of the modern industry, theconfliction between supplying and demanding of energy has becomeincreasingly acute. China is a major energy consumer and meanwhile amajor country of energy shortage with an urgent desire for searchingreplaceable energy sources. Ethanol is a clean energy source with a goodmutual solubility which can be used as blending component added intogasoline, to partially replace gasoline and improve the octane numberand the oxygen content of gasoline. It can also promote gasoline burningsufficiently and decrease the emission of carbon monoxide andhydrocarbons in vehicle exhaust. As a partial replacement of vehiclefuel, ethanol may make the vehicle fuel in China more diversified.Currently, in China cereals, especially corns, has mostly been used as araw material to manufacture fuel ethanol. China has become the thirdlargest country of ethanol producing and consuming, after Brazil andAmerica. However, according to Chinese national condition, there aremany unfavorable factors using cereals as raw material to produceethanol. In the future, non-cereal routes for producing ethanol will bedeveloped preferably in China.

Started with coal resources, producing ethanol via syngas is animportant direction to develope coal chemical engineering industry inChina with a broad market prospect. It has great strategic meanings andfar-reaching impacts on clean utilization of coal resources, relievingthe pressure of lacking oil resources and enhancing energy security inour country. Currently, there are mainly two process routes of preparingethanol from coal, one of which is preparing ethanol from syngasdirectly. However, a precious metal, rhodium, is needed to serve as thecatalyst in this route, so the cost of the catalyst is relatively high.Moreover, the output of rhodium is limited. The other route is preparingethanol from syngas through hydrogenation of acetic acid, in whichacetic acid is preformed by liquid phase methanol carbonylation from thesyngas, and then converts to ethanol by hydrogenation. The second routeis mature, but the device used in this route needed to be made ofspecial alloy which is anticorrosive, so the cost is high.

Using dimethyl ether as raw material, methyl acetate can be directlysynthetized by carbonylation of dimethyl ether, and methyl acetate canbe hydrogenated to ethanol. Although the route is still in researchstage, it is a brand new route with great application prospect. In 1983,Fujimoto (Appl Catal 1983, 7 (3), 361-368) used Ni/Ac as catalyst tocarry out a gas-solid phase reaction of dimethyl ether carbonylation. Itwas discovered that dimethyl ether can react with CO to generate methylacetate when the molar ratio of CO/DME is in a range from 2.4 to 4, withselectivity in a range from 80% to 92% and the highest yield of 20%. In1994, Wegman (J Chem Soc Chem Comm 1994, (8), 947-948) carried out adimethyl ether carbonylation reaction using heteropolyacid RhW₁₂PO₄SiO₂as the catalyst. The yield of methyl acetate was 16% and nearly no otherside products were generated. In 2002, Russian researchers, Volkova andher colleagues (Catalysis Letters 2002, 80 (3-4), 175-179) used a cesiumphosphotungstate modified Rh as catalyst to carry out the carbonylationreaction of dimethyl ether and the reaction rate is an order ofmagnitude higher than the Wegman's reaction using RhW₁₂PO₄SiO₂ ascatalyst.

In 2006, Enrique Iglesia's research group in Berkeley (Angew. Chem, Int.Ed. 45(2006) 10, 1617-1620, J. Catal. 245 (2007) 110, J. Am. Chem. Soc.129 (2007) 4919) carried out dimethyl ether carbonylation on themolecular sieves with 8 membered ring and 12 membered ring or 10membered ring, such as Mordenite and Ferrierite. As a result, it wasconsidered that the carbonylation reaction happenes on the B acid activecenter of 8 membered ring. The selectivity of methyl acetate was quitegood, reaching 99%, but the activity of dimethyl ether carbonylation isvery low.

American application US2007238897 disclosed that using molecular sieveswith 8 membered ring pore structure, such as MOR, FER and OFF, ascatalyst for the carbonylation of ethers, the pore size of the 8membered ring should be larger than 0.25×0.36 nm. Using mordenite ascatalyst under the reaction conditions of 165° C. and 1 MPa, aspace-time yield of 0.163-MeOAc(g-Cat·h)⁻¹ was achieved. WO2008132450A1(2008) disclosed a MOR catalyst modified by copper and silver, whoseperformance is obviously better than unmodified MOR catalyst, onreaction conditions of hydrogen atmosphere and temperature ranging from250° C. to 350° C. WO2009081099A1 disclosed that the carbonylationperformance of MOR catalyst with smaller grains is better than MORcatalyst with bigger grains. WO2010130972A2 disclosed an MOR catalysttreated by desilication and dealuminzation, and the activity and thereaction stability of the MOR catalyst can be significantly enhanced byan optimized combination of acid treatment and alkali treatment.Moreover, CN103896769A disclosed a method for preparing methyl acetateby carbonylation of dimethyl ether, in which mordenite and/or ferrieritewere used as the catalyst. CN101903325A disclosed a carbonylationprocess of preparing acetic acid and/or methyl acetate in which themolecular sieves with MOR framework structure were used as the catalyst.CN101687759A disclosed a method for carbonylating methyl ether in whichzeolites with MOR, FER, OFF or GME framework structures were used,specifically such as mordenite, ferrierite, offretite and gmelinite.Wang Donghui (“Application of a cocrystallization molecular sievecatalyst in preparing methyl acetate by carbonylation of dimethylether”, Chemical Production and Techniques (2013), No. 3, Vol 20, 14-18)disclosed an application of a cocrystallization molecular sieve catalystin preparing methyl acetate by carbonylation of dimethyl ether, in whichthe catalyst was a cocrystallization molecular sieve containing 2 phasesof BEA/MOR. And cocrystallization molecular sieve containing 2 phases ofEMT/FAU was mentioned in the first paragraph, without being used forcarbonylation of dimethyl ether to methyl acetate. CN102950018Adisclosed the reaction data of dimethyl ether carbnylation on acocrystallization molecular sieve of rare earth ZSM-35/MOR. The resultsshow that the activity and stability of cocrystallization molecularsieve was significantly better than ZSM-35 catalyst, and the stabilityof cocrystallization molecular sieve was significantly better than MORcatalyst. Xu Longya and his colleagues (RSC Adv. 2013, 3:16549-16557)also reported the reaction properties of ZSM-35 treated by alkali incarbonylation of dimethyl ether. The results show that after beingtreated by alkali, ZSM-35 has an apparent mesoporous structure,enhancing the diffusion effects of reactants and products on thecatalyst, and the stability and activity of the catalyst was improved.

In CN101613274A, pyridine organic amines were used to modify mordenitemolecular sieve catalyst, and it was discovered that the modification ofmolecular sieve can dramatically enhance the stability of catalyst. Thepercent conversion of dimethyl ether was in a range from 10% to 60%, andthe selectivity of methyl acetate was over 99%. Moreover, the activityof the catalyst remained stable after reacting for 48 h. Shen Wenjie(Catal. Lett. 2010, 139:33-37) and his colleagues made a research onpreparing methyl acetate by carbonylation of dimethyl ether, comparingthe reaction activity on MOR and ZSM-35 catalyst. It was discovered thatZSM-35 molecular sieve has better reaction stability and productsselectivity, and under the reaction conditions of 250 □, 1 MPa,DME/CO/N₂/He=5/50/2.5/42.5 and 12.5 mL/min, the percent conversion ofdimethyl ether could reach 11%, and the selectivity of methyl acetatecould reach 96%.

The above references has disclosed a lot of research results on dimethylether carbonylation, and research on the catalyst has mainly focused onMOR, FER, and the like with a structure of 8 membered ring. In theresults reported publicly, those catalysts are very easy to becomeinactivated with catalyst life of less than 100 h. And additionally, thereaction results cannot meet the requirement of industrial production.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a new method forproducing light fatty acid alkyl ester.

The inventors of the present invention found that the carbonylationreaction of low alkyl ether is a typical acid catalyzed reaction, andthe acidity and pore structure of the catalyst have a decisive influenceon the catalytic performance of the catalyst. EMT zeolite belongs to thehexagonal system, the space group of P₆₃/mmc with the cell parameters ofa=b=1.7374 nm and c=2.8365 nm, and the framework density of 12.9 T/nm³.Its framework structure is a simple hexagonal analogue of faujasitezeolite FAU, composed of 12 membered rings, 6 membered rings and 4membered rings. As a zeolite with a better topology structure than FAU,it has a stronger acidity and a bigger acid quantity. At the same time,EMT has two sets of intersecting cavities which are connected by 2dimensional cross channels. Its superior pore connectivity is moreconducive to the adsorption of reactants and the diffusion of productmolecules.

Therefore, the present invention provides a method for producing fattyacid alkyl ester with formula of R₁—COO—R₂, which comprises a stepcarrying out a carbonylation reaction of a alkyl ether with formula ofR₁—O—R₂ and a raw gas containing carbon monoxide in the presence of acatalyst containing an acidic EMT zeolite molecular sieve; wherein R₁and R₂ are independently selected from C₁-C₄ alkyl groups. Preferably,the R₁ and the R₂ are independently selected from CH₃—, CH₃CH₂—,CH₃(CH₂)₂—, (CH₃)₂CH—, CH₃(CH₂)₃— or (CH₃)₃CH—. More preferably, both ofthe R₁ and the R₂ are CH₃—.

In a preferred embodiment, the molar ratio of silicon atoms to aluminumatoms in the acidic EMT zeolite molecular sieve is in a range from 1.5to 30. Preferably, the molar ratio of silicon atoms to aluminum atoms inthe acidic EMT zeolite molecular sieve is in a range from 2 to 15.

In a preferred embodiment, the acidic EMT zeolite molecular sievecontains a catalyst promoter which is one or more metals selected fromgallium, iron, copper and silver.

Preferably, the catalyst promoter is introduced to the acidic EMTzeolite molecular sieve by a method selected from in-situ synthesis,metal ion exchange or impregnation loading. More preferably, based onthe total weight of the catalyst, the weight fraction of the catalystpromoter calculated by weight of metal elementary substance is in arange from 0.01 wt % to 10 wt %.

In a preferred embodiment, the acidic EMT zeolite molecular sievecontains a binder which is one or more compounds selected from alumina,silicon dioxide and magnesium oxide.

Preferably, based on the total weight of the catalyst, the weightfraction of the binder is in a range from 0 wt % to 50 wt %.

In a preferred embodiment, the fatty acid alkyl ester is furtherhydrolyzed to a corresponding carboxylic acid. Preferably, thecorresponding carboxylic acid is acetic acid.

In a preferred embodiment, the fatty acid alkyl ester is furtherhydrogenated to a corresponding alcohol. Preferably, the correspondingalcohol is ethyl alcohol.

In a preferred embodiment, the raw gas containing carbon monoxidecontains carbon monoxide, hydrogen and one or more inactive gasesselected from nitrogen, helium, argon, carbon dioxide, methane andethane. Preferably, based on the total volume of the raw gas containingcarbon monoxide, the volume fraction of carbon monoxide is in a rangefrom 50% to 100%, and the volume fraction of hydrogen is in a range from0% to 50%, and the volume fraction of the inert gas is in a range from0% to 50%.

In a preferred embodiment, the carbonylation reaction is carried out ata temperature range from 170 □ to 240 □ and at a pressure range from 1MPa to 15 MPa.

In a preferred embodiment, the carbonylation reaction is carried out ina fixed bed reactor, a fluidized bed reactor or a moving bed reactor.

The present invention provides a new method for producing light fattyacid alkyl esters, especially a new method for producing methyl acetate.In the method of the present invention, the carbonylation is carried outin the presence of the catalyst containing the acidic EMT zeolitemolecular sieve, and the reaction activity is high, and the stabilityhas been significantly improved, meeting the requirement of industrialproduction.

DETAILED DESCRIPTION OF THE EMBODIMENT

The present invention provides a method for synthesizing fatty acidalkyl ester with formula of R₁—COO—R₂, which comprises a step carryingout a carbonylation reaction of an alkyl ether with formula of R₁—O—R₂and a raw gas containing carbon monoxide on a catalyst containing anacidic EMT zeolite molecular sieve. Preferably, the carbonylationreaction is carried out under the conditions without water or with tracewater. R₁ and R₂ are independently selected from C₁-C₄ alkyl groups,such as CH₃—, CH₃CH₂—, CH₃(CH₂)₂—, (CH₃)₂CH—, CH₃(CH₂)₃— or (CH₃)₃CH—.

In the present invention, the term ‘light fatty acid alkyl ester’ refersto the fatty acid alkyl ester expressed in formula of R₁—COO—R₂, whereinR₁ and R₂ are independently selected from C₁-C₄ alkyl groups.

In a particular embodiment, the present invention provides a method forproducing methyl acetate by carbonylation reaction of dimethyl ether andcarbon monoxide on an acidic zeolite molecular sieve catalyst with EMTtopological structure.

Preferably, the molar ratio of silicon atoms to aluminum atoms in theacidic EMT zeolite molecular sieve used in the present invention is in arange from 1.5 to 30. Preferably, the molar ratio of silicon atoms toaluminum atoms in the acidic EMT zeolite molecular sieve of the presentinvention is in a range from 2 to 15.

Preferably, the acidic EMT zeolite molecular sieve used in the presentinvention contains a catalyst promoter which is one or more metalsselected from gallium, iron, copper and silver (which may exist in theform of metal elementary substance or metal compounds such as metaloxides). For instance, the catalyst promoter is introduced to the acidicEMT zeolite molecular sieve by a method selected from in-situ synthesis,metal ion exchange or impregnation loading. Preferably, based on thetotal weight of the catalyst, the weight fraction of the catalystpromoter calculated by weight of metal elementary substance is in arange from 0.01 wt % to 10 wt %.

Preferably, the acidic EMT molecular sieve used in the present inventioncontains a binder which is one or more compounds selected from alumina,silicon dioxide and magnesium oxide. Preferably, the weight fraction ofthe binder in the total weight of the catalyst is in a range from 0 wt %to 50 wt %.

Preferably, the raw gas containing carbon monoxide used in the presentinvention contains carbon monoxide, hydrogen and one or more inactivegases selected from nitrogen, helium, argon, carbon dioxide, methane andethane. Preferably, based on the total volume of the raw gas containingcarbon monoxide, the volume fraction of carbon monoxide is in a rangefrom 50% to 100%, and the volume fraction of hydrogen is in a range from0% to 50%, and the volume fraction of the inert gas is in a range from0% to 50%.

Preferably, the alkyl ether used in the present invention is dimethylether, and the fatty acid alkyl ester obtained after carbonylation ismethyl acetate.

Preferably, the fatty acid alkyl ester synthesized by the method of thepresent invention can be further hydrolyzed to a correspondingcarboxylic acid. For instance, the methyl acetate obtained above can beused to produce acetic acid.

Preferably, the raw gas containing carbon monoxide used in the presentinvention can also contain hydrogen and an inactive gas. The inactivegas can be one or more inactive gases selected from nitrogen, helium,argon, carbon dioxide, methane and ethane.

Preferably, the carbonylation reaction in the present invention iscarried out at a temperature range from 170 □ to 240 □ and at a pressurerange from 1 MPa to 15 MPa.

Preferably, the carbonylation reaction in the present invention iscarried out in a fixed bed reactor, a fluidized bed reactor or a movingbed reactor.

In addition, although no special restrictions are required, the molarratio of dimethyl ether and carbon monoxide is preferably in a rangefrom 1:20 to 1:0.5 in a preferred carbonylation reaction.

EXAMPLES

The present invention will be described in details by Examples, but thepresent invention is not limited to these Examples.

In the examples, the calculation of percent conversion of alkyl ether(represented by dimethyl ether) and selectivity of light fatty acidalkyl ester (represented by methyl acetate) was based on the carbon molenumber:

Percent conversion of dimethyl ether=[(the carbon mole number ofdimethyl ether in the feed gas)−(the carbon mole number of dimethylether in the product)]+(the carbon mole number of dimethyl ether in thefeed gas)×(100%)

Selectivity of methyl acetate=(⅔)×(the carbon mole number of methylacetate in the product)+[(the carbon mole number of dimethyl ether inthe feed gas)−(the carbon mole number of dimethyl ether in theproduct)]×(100%)

Four samples of Na-EMT zeolite molecular sieve whose molar ratios ofsilicon atom to aluminum atom respectively are 2, 4, 15 and 25, a sampleof Na-EMT zeolite molecular sieve containing Ga whose molar ratio ofsilicon atom to aluminum is 4, and a sample of Na-EMT zeolite molecularsieve containing Fe whose molar ratio of silicon atom to aluminum is 4have been used in the Examples. All of them were produced and providedby Dalian Institute of Chemical Physics.

Examples for Preparing the Catalyst H-EMT Catalyst

100 g of a sample of Na-EMT zeolite molecular sieve was exchanged with0.5 mol/L of ammonium nitrate for three times and each time was for 2hours. And then the solid product was washed with deionized water,dried, calcined at 550° C. for 4 h, pressed, crushed and sieved to 20-40mesh used as the catalyst sample. Four samples of Na-EMT zeolitemolecular sieve with molar ratios of silicon atom to aluminum atom of 2,4, 15 and 25 were used, to obtain the samples of Catalyst 1#, Catalyst2#, Catalyst 3# and Catalyst 4#, respectively.

Ga-EMT Catalyst

100 g of the sample of Na-EMT zeolite molecular sieve containing Ga (themolecular ratio of silicon atom to aluminum is 4) was exchanged with 0.5mol/L of ammonium nitrate for three times and each time was for 2 hours.And then the solid product was washed with deionized water, dried,calcined at 550° C. for 4 h, pressed, crushed and sieved to 20-40 meshto obtain the sample of Catalyst 5#.

Fe-EMT Catalyst

100 g of the sample of Na-EMT zeolite molecular sieve containing Fe (themolecular ratio of silicon atom to aluminum is 4) was exchanged with 0.5mol/L of ammonium nitrate for three times and each time was for 2 hours.And then the solid product was washed with deionized water, dried,calcined at 550° C. for 4 h, pressed, crushed and sieved to 20-40 meshto obtain the sample of Catalyst 6#.

Supported Catalyst of M/EMT

The supported catalyst of M/EMT was prepared using equivalent-volumeimpregnation method. 4.32 g of Fe(NO₃)₃, 4.32 g of Cu(NO₃)₂.3H₂O and3.04 g of AgNO₃.3H₂O were respectively dissolved in 18 mL of deionizedwater to form the Fe(NO₃)₃ aqueous solution, Cu(NO₃)₂ aqueous solutionand AgNO₃ aqueous solution. 20 g of Catalyst 2# (H-EMT zeolite molecularsieve catalyst) was added into the Fe(NO₃)₃ aqueous solution, Cu(NO₃)₂aqueous solution and AgNO₃ aqueous solution, respectively. Afterstanding for 24 hours, the solid products were separated, washed bydeionized water, dried in the oven at 120 □ for 12 hours, and then thesamples obtained were put into a muffle furnace whose temperature washeated to 5500 at a heating rate of 2° C./min, calcined at 550° C. inair for 4 h to obtain the samples of Catalyst 7#, Catalyst 8# andCatalyst 9#.

Ion Exchange Catalyst of M-EMT

20 g of Catalyst 2# (H-EMT zeolite molecular sieve catalyst) and 300 mLof 0.15 mol ferric nitrate aqueous solution were placed in a flask,being stirred for 2 hours at 800 under the condition of cooling andrefluxing with solid-liquid ratio of 1:15. The solid product wasseparated by filtration and washed by deionized water. Repeating theabove steps for 2 times, the sample obtained was dried at 1200 for 12hours, and the dried sample was put into a muffle furnace whosetemperature was heated to 5500 at a heating rate of 2° C./min, calcinedat 550° C. in air for 4 h to obtain the sample of Catalyst 10#.

Molded Catalyst of H-EMT

80 g of Na-EMT zeolite molecular sieve with molar ratio of silicon atomto aluminum of 4, 28 g of pseudo-boehmite and 10% of diluted nitric acidwere uniformly mixed, and then the mixture was molded through extrusion.After being calcined at 550 □ for 4 hours, the molded sample wasexchanged with 0.5 mol/L of ammonium nitrate for three times (2hours/time). And then the solid product was washed by deionized water,dried, calcined at 550° C. for 4 h to obtain the sample of Catalyst 11#.

80 g of Na-EMT zeolite molecular sieve with molar ratio of silicon atomto aluminum of 4, 20 g of magnesium oxide and 10% of diluted nitric acidwere uniformly mixed, and then the mixture was molded through extrusion.After being calcined at 550 □ for 4 hours, the molded sample wasexchanged with 0.5 mol/L of ammonium nitrate for three times and eachtime was for 2 hours. And then the solid product was washed by deionizedwater, dried, calcined at 550° C. for 4 h to obtain the sample ofCatalyst 12#.

80 g of Na-EMT zeolite molecular sieve with molar ratio of silicon atomto aluminum of 4, 50 g of silicon sol and 10% of diluted nitric acidwere uniformly mixed, and then the mixture was molded through extrusion.After being calcined at 550 □ for 4 hours, the molded sample wasexchanged with 0.5 mol/L of ammonium nitrate for three times (2hours/time). And then the solid product was washed by deionized water,dried, calcined at 550° C. for 4 h to obtain the sample of Catalyst 13#.

Examples of Synthesis Comparative Example

H-MOR (molar ratio of silicon atom to aluminum atom Si/A=6.7) was usedas a comparative catalyst. 10 g of the comparative catalyst was put intoa tubular fixed bed reactor with inner diameter of 28 mm, and then washeated to 550 □ at a heating rate of 5 □/min under nitrogen gas. Afterbeing kept at 550 □ for 4 hours, the temperature was reduced to thereaction temperature of 190 □ in nitrogen gas, and then the pressure wasincreased to the reaction pressure of 5 MPa by introducing CO. The spacevelocity of feeding dimethyl ether was 0.10 h⁻¹, and the molar ratio ofdimethyl ether to carbon monoxide was 1:6, and the molar ratio of carbonmonoxide to hydrogen in the raw gas containing carbon monoxide was 2:1.The results at the time on stream (TOS) of 1 h, 50 h and 100 h, areshown in Table 1.

TABLE 1 Results of the comparative catalyst Time on stream (h) 1 50 100Percent conversion of dimethyl ether (%) 35.7 23.8 9.8 Selectivity ofmethyl acetate (%) 99.8 78.2 25.3

Example 1

According to Table 2, 10 g of the catalyst was put into a tubular fixedbed reactor with inner diameter of 28 mm, and then was heated to 550 □at a heating rate of 5 □/min under nitrogen gas. After being kept at 550□ for 4 hours, the temperature was reduced to the reaction temperatureof 190 □ in nitrogen gas, and then the pressure was increased to thereaction pressure of 5 MPa by introducing CO. The space velocity offeeding dimethyl ether was 0.10 h⁻¹, and the molar ratio of dimethylether to carbon monoxide was 1:6, and the molar ratio of carbon monoxideto hydrogen in the raw gas containing carbon monoxide was 2:1. Theresults are shown in Table 2.

TABLE 2 Evaluation results of catalyst for dimethyl ether carbonylationTOS = 1 h TOS = 50 h TOS = 100 h Percent Percent Percent conversionSelectivity conversion of Selectivity conversion of Selectivity ofdimethyl of methyl dimethyl ether of methyl dimethyl ether of methylCatalyst ether (%) acetate (%) ether (%) acetate (%) ether (%) acetate(%)  1# 8.1 99.8 7.9 99.2 7.5 95.3  2# 22.1 99.7 21.3 99.2 17.5 95.3  3#34.7 99.6 31.8 98.3 23.5 97.7  4# 29.1 99.1 28.9 98.2 24.5 96.3  5# 30.798.3 29.8 97.3 27.5 91.6  6# 32.7 98.3 32.8 97.3 31.5 91.6  7# 27.7 98.326.8 97.3 24.5 91.6  8# 28.3 98.3 27.8 97.3 25.3 91.6  9# 28.2 98.3 27.397.3 24.2 91.6 10# 30.7 98.3 29.8 97.3 26.8 91.6 11# 19.1 99.9 18.3 99.217.5 98.3 12# 17.1 99.1 16.3 98.7 15.5 97.3 13# 15.1 99.3 14.3 98.2 14.297.3 TOS: Time on stream

Example 2

Reaction results of dimethyl ether carbonylation at different reactiontemperatures 10 g of Catalyst 3# was put into a tubular fixed bedreactor with inner diameter of 28 mm, and then was heated to 550 □ at aheating rate of 50/min under nitrogen gas. After being kept at 550 □ for4 hours, the temperature was reduced to the reaction temperature innitrogen gas, and then the pressure was increased to the reactionpressure of 5 MPa by introducing CO. The raw material went through thecatalyst bed from top to bottom. The space velocity of feeding dimethylether was 0.10 h⁻¹, and the molar ratio of carbon monoxide to dimethylether was 6:1, and the molar ratio of carbon monoxide to hydrogen in theraw gas containing carbon monoxide was 2:1. The results at the reactiontime when the catalytic reaction ran on for 100 h are shown in Table 3.

TABLE 3 Reaction results of dimethyl ether on H-EMT catalyst atdifferent reaction temperatures Reaction temperature (□) 170 200 230 240Percent conversion of dimethyl ether (%) 15.7 42.1 76.0 87.8 Selectivityof methyl acetate (%) 97.8 99.7 94.5 90.4

Example 3 Reaction Results of Dimethyl Ether Carbonylation at DifferentReaction Pressures

The Catalyst 4# was used. The reaction pressures were 1 MPa, 6 MPa, 10MPa and 15 MPa, respectively, and other experimental conditions weresame as Example 1. The results at the reaction time when the catalyticreaction ran on for 100 h are shown in Table 4.

TABLE 4 Reaction results of dimethyl ether on H-EMT catalyst atdifferent reaction pressures Reaction pressure (MPa) 1 6 10 15 Percentconversion of dimethyl ether (%) 18.3 29.3 41.8 52.3 Selectivity ofmethyl acetate (%) 98.7 99.1 99.4 99.8

Example 4 Reaction Results of Dimethyl Ether Carbonylation at DifferentSpace Velocities of Dimethyl Ether

The Catalyst 6# was used. The space velocities of dimethyl ether were0.25 h⁻¹, 1 h⁻¹ and 2h⁻¹, respectively, and other experimentalconditions were same as Example 1. The results at the

reaction time when the catalytic reaction ran on for 100 h are shown inTable 5.

TABLE 5 Reaction results of dimethyl ether on H-EMT catalyst atdifferent space velocities of dimethyl ether Space velocity of dimethylether (h⁻¹) 0.25 1 2 Percent conversion of dimethyl ether (%) 18.3 14.310.8 Selectivity of methyl acetate (%) 99.7 99.1 97.9

Example 5 Reaction Results of Dimethyl Ether Carbonylation UnderDifferent Molar Ratio of Dimethyl Ether to Carbon Monoxide

The Catalyst 6# was used. The molar ratios of carbon monoxide todimethyl ether were 12:1, 8:1, 4:1 and 2:1, respectively, and otherexperimental conditions were same as Example 1. The results at thereaction time when the catalytic reaction ran on for 100 h are shown inTable 6.

TABLE 6 Reaction results of dimethyl ether on H-EMT catalyst underdifferent molar ratio of dimethyl ether to carbon monoxide Mole ratio ofcarbon monoxide/dimethyl ether 1:12 1:8 1:4 1:2 Percent conversion ofdimethyl ether (%) 43.6 36.7 18.8 12.3 Selectivity of methyl acetate (%)97.8 98.1 99.5 99.4

Example 6

Reaction Results of Dimethyl Ether Carbonylation when the Raw GasContaining Carbon Monoxide Also Contains an Inactive Gas

The Catalyst 9# was used. The space velocities of dimethyl ether was 0.1h⁻¹, and the molar ratio of dimethyl ether to carbon monoxide was 1:9,and the reaction temperature was 190 □, and other experimentalconditions were same as Example 1. The results at the reaction time whenthe catalytic reaction ran on for 200 h are shown in Table 7.

TABLE 7 Reaction results of dimethyl ether on H-EMT catalyst when theraw gas containing carbon monoxide also contains an inactive gas PercentSelectivity Volume conversion of of methyl Volume fraction of fractionof dimethyl ether acetate inert gas CO (%) (%)  1% (H₂) 99% 33.5 96.848% (H₂) 52% 13.9 97.8  1% (N₂) 99% 33.5 96.5 48% (N₂) 52% 12.6 95.2 20%(N₂) + 28% (H₂) 52% 13.1 96.7 20% (CO₂) + 28% (H₂) 52% 13.2 96.7

Example 7 Reaction Results in Different Type of Reactors

The Catalyst 2# was used. The reaction temperature was 230 □, and thereactors were a fluidized bed reactor and a moving bed reactor,respectively, and other experimental conditions were same as Example 1.The reaction results are shown in Table 8.

TABLE 8 Reaction results on H-EMT catalyst in different type of reactorsType of reactor fluidized bed moving bed Percent conversion of ofdimethyl ether (%) 89.2 91.5 Selectivity of methyl acetate (%) 98.7 98.5

Example 8

Reaction Results on H-EMT Catalyst when the Alkyl Ether is not DimethylEther

The R₁ and R₂ were same group and both were not methyl, and otherexperimental conditions were same as Example 1. The reaction results areshown in Table 9.

TABLE 9 Reaction results on H-EMT catalyst when the alkyl ether is notdimethyl ether Percent conversion Selectivity of R₁—O—R₂ of R—COO—R R₁R₂ (%) (%) CH₃CH₂— CH₃CH₂— 30.6 98.2 CH₃(CH₂)₂— CH₃(CH₂)₂— 28.7 97.8(CH₃)₃CH— (CH₃)₃CH— 26.8 98.8

Example 9 Methyl Acetate Hydrolysis to Acetic Acid

The carbonylation product methyl acetate was hydrolyzed to acetic acidin the presence of hydrolyzing catalyst. The ratio of water to ester was4, and space velocity of methyl acetate was 0.4 h⁻¹, and loading amountof the catalyst was 10 g. The reaction results are shown in Table 10.

TABLE 10 Reaction result of methyl acetate hydrolysis to acetic acidReaction temperature (□) 50 60 70 Percent conversion of methyl acetate(%) 55.7 72.1 89.0

Example 10 Methyl Acetate Hydrogenation to Ethanol

The carbonylation product methyl acetate was hydrogenated to ethanol inthe presence of hydrogenation catalyst. The reaction pressure was 5.5MPa, and the molar ratio of hydrogen tp methyl acetate in raw gas was20:1, and the molar ratio of hydrogen to carbon monoxide was 20:1, andthe space velocity of methyl acetate was 3 h⁻¹, and loading amount ofthe catalyst was 10 g. The reaction results are shown in Table 11.

TABLE 11 Reaction results of methyl acetate hydrogenation to ethanolMethyl acetate hydrogenation Reaction Percent conversion SelectivitySelectivity temperature of methyl acetate of Ethanol of Methanol (□) (%)(%) (%) 180 68.1 39.7 53.2 200 77.4 41.0 51.8 220 88.3 43.3 50.1 24096.2 45.2 50.3

The present invention has been described in detail as above, but theinvention is not limited to the detailed embodiments described in thistext. Those skilled in the art will understand that other changes anddeformations can be made without deviating from the scope of theinvention. The scope of the invention is limited by the appended claims.

1. A method for producing fatty acid alkyl ester with formula ofR₁—COO—R₂, which comprises a step in which an alkyl ether with formulaof R₁—O—R₂ and a raw gas containing carbon monoxide go through a reactorloaded with a catalyst for carrying out a carbonylation reaction;wherein the catalyst contains an acidic EMT zeolite molecular sieve;wherein R₁ and R₂ are independently selected from C₁-C₄ alkyl groups. 2.A method for producing fatty acid alkyl ester with formula of R₁—COO—R₂according to claim 1, wherein in the acidic EMT zeolite molecular sieve,the molar ratio of silicon atoms to aluminum atoms is in a range from1.5 to
 30. 3. A method for producing fatty acid alkyl ester with formulaof R₁—COO—R₂ according to claim 1, wherein the acidic EMT zeolitemolecular sieve contains a catalyst promoter which is one or more metalsselected from gallium, iron, copper and silver.
 4. A method forproducing fatty acid alkyl ester with formula of R₁—COO—R₂ according toany of claims 1 to 3, wherein the acidic EMT zeolite molecular sievecontains a binder which is one or more compounds selected from alumina,silicon dioxide and magnesium oxide.
 5. A method for producing fattyacid alkyl ester with formula of R₁—COO—R₂ according to claim 1, whereinthe R₁ and the R₂ are independently selected from CH₃—, CH₃CH₂—,CH₃(CH₂)₂—, (CH₃)₂CH—, CH₃(CH₂)₃— or (CH₃)₃CH—.
 6. A method forproducing fatty acid alkyl ester with formula of R₁—COO—R₂ according toclaim 1, wherein the fatty acid alkyl ester is hydrolyzed to acorresponding carboxylic acid.
 7. A method for producing fatty acidalkyl ester with formula of R₁—COO—R₂ according to claim 1, wherein thefatty acid alkyl ester is hydrogenated to a corresponding alcohol.
 8. Amethod for producing fatty acid alkyl ester with formula of R₁—COO—R₂according to claim 1, wherein the raw gas containing carbon monoxidecontains carbon monoxide, hydrogen and one or more inactive gasesselected from nitrogen, helium, argon, carbon dioxide, methane andethane.
 9. A method for producing fatty acid alkyl ester with formula ofR₁—COO—R₂ according to claim 1, wherein the carbonylation reaction iscarried out at a temperature range from 170° C. to 240° C. and at apressure range from 1 MPa to 15 MPa.
 10. A method for producing fattyacid alkyl ester with formula of R₁—COO—R₂ according to claim 1, whereinthe carbonylation reaction is carried out in a fixed bed reactor, afluidized bed reactor or a moving bed reactor.
 11. A method forproducing fatty acid alkyl ester with formula of R₁—COO—R₂ according toclaim 1, wherein in the acidic EMT zeolite molecular sieve, the molarratio of silicon atoms to aluminum atoms is in a range from 2 to
 15. 12.A method for producing fatty acid alkyl ester with formula of R₁—COO—R₂according to claim 3, wherein the catalyst promoter is introduced to theacidic EMT zeolite molecular sieve by a method selected from in-situsynthesis, metal ion exchange or impregnation loading.
 13. A method forproducing fatty acid alkyl ester with formula of R₁—COO—R₂ according toclaim 3, wherein based on the total weight of the catalyst, the weightfraction of the catalyst promoter calculated by weight of metalelementary substance is in a range from 0.01 wt % to 10 wt %.
 14. Amethod for producing fatty acid alkyl ester with formula of R₁—COO—R₂according to claim 4, wherein based on the total weight of the catalyst,the weight fraction of the binder is in a range from 0 wt % to 50 wt %.15. A method for producing fatty acid alkyl ester with formula ofR₁—COO—R₂ according to claim 8, wherein based on the total volume of theraw gas containing carbon monoxide, the volume fraction of carbonmonoxide is in a range from 50% to 100%, and the volume fraction ofhydrogen is in a range from 0% to 50%, and the volume fraction of theinert gas is in a range from 0% to 50%.